Wiring Third Brake Light and Dome Light on a Leer Camper Shell on 2007 GMC Sierra 2500 HD New Body

Updated 05/14/2015 | Published 05/13/2015

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Question:

Trying to wire topper and Im getting different information. Some say you have to run a wire from the interior trailer wire bundle orange wire by the brake pedal all the way to the back. I also hear that you can tap into a light blue wire in the trailer bundle near the rear of the truck. Then I hear you have to wire some module into the rear so the third brake light doesnt flash when you activate the turn signals. So I decided to check with the experts. You guys. Whats the easiest way for this novice to wire this thing. My truck is the new body style which I think makes a difference. Thanks in advance for any help you can throw my way.

asked by: Duane

Expert Reply:

The one place I know for sure to access the CHMSL circuit on your 2007 New Body Sierra is under the dash. You will need to look for a wire bundle under the dash, to the left of the steering column. There should be a white tag holding the wire bundle together.

There should be an orange wire and that is the CHMSL wire. You can attach a length of wire to this orange wire, route it through the firewall, under the truck, and to where ever it needs to go on the camper shell. Be sure to avoid areas that may pinch or burn the wire. You can use zip ties to secure the wire to the under side of the truck.

Another option is to check with a local place that sells/installs camper shells. They may know of an easier place to access the CHMSL wire closer to the camper shell.

it is possible that light blue wire you mentioned would work but you would need to use a circuit tester such as # PTW2993 to make sure it only has power with the brake lights and not any other functions.

To power the dome light you could use a switch, such as # PK34513, to the vehicle battery and out to the dome light and turn it on/off as needed.

expert reply by: Michael H